Back rub is a form of physical therapy that involves rubbing and kneading the back muscles to relieve tension and pain. The term 'back rub' can be broken down into three parts: AAH (3 letters), ACHE (4 letters), and MASSAGE (7 letters). AAH stands for 'Apply and Hold, ' which is a technique used to apply pressure to the back muscles. ACHE stands for 'Alternating Compression and Heat Exchange, ' which is a method of alternating between heat and cold to reduce inflammation and pain. Finally, MASSAGE stands for 'Manual Assisted Soft Tissue Mobilization, ' which is a type of MASSAGE that uses hands-on techniques to manipulate the soft tissues of the body. All of these techniques are used together to provide relief from back pain and tension.